1. Field of the Invention
The present invention relates to an apparatus for successive application of two coats of liquid or pasty medium on one side of a traveling web of material, notably of paper or cardboard.
2. Description of the Related Art
An apparatus of this type is known, e.g., from German Document No. 43 02 437 A1. With this coating system, a first layer of a coating medium is applied with a first applicator on one side of a traveling web of material, and the material web is then passed through an arrangement of drying apparatuses. Next, a second coat of a coating medium is applied with a second applicator on the side of the material web that was previously provided with the first coat, and the material web passes then again through various drying apparatuses. The two applicators are designed such that an applicator nozzle applies the coating medium on the surface of an applicator roll, and the coating medium transfers in a press nip from the surface of the applicator roll to the material web. In both of the two applicators the press nip is formed between an applicator roll and a backing roll, and the material web passes through the press nip. In one embodiment of the prior coating system, a nozzle applicator is associated also with each of the two backing rolls, so that the backing rolls themselves act also as applicator rolls and the back side of the traveling material web can be provided as well with two coats of a coating medium.
This prior coating system, however, requires a large amount of physical space in order to accommodate the two applicators and the pertaining drying apparatuses as well as the pertaining elements for web routing.